Hazrat Thabit Banani says: It has reached us that the Prophet Dawud (peace be upon him) had designated places in his houses as prayer mats for his wives and children. Whether it was a time during the day or a part of the night, at all times someone from his household would be engaged in prayer on those mats. Thus, this verse is general for all those (family members) (who participated in this good deed): O family of Dawud, give thanks (to your Lord), and few of My servants are truly grateful.